Passing the northernmost tip of Eurasia

Jorien Vonk, just passing the northernmost tip of Eurasia in the Vilkitskiy Strait, August 21, 2008

Since a few days, the expedition has really gotten up to speed. Örjan wrote yesterday about the fact that all our different sampling systems are up and running now. And we have even started to make ourselves at home in the lab containers that serve as working space for all the long days onboard. This means of course coffee brewers with Swedish coffee, loud music to hide the sounds of running pumps, camera’s and binoculars handy for islands or birds that appear, and a huge map of the Arctic Ocean on the wall where we mark our route.

One of our main sampling activities onboard is to take sediment cores with our Gemini corer (see picture). By letting this heavy corer sink into the sediment simple gravity!) we collect two cores at the same time. This gives us a unique chance to look back in time and to look for example at the effects of recent climatic changes. The Russian Arctic is known for its huge areas of permanently frozen peatland that store massive amounts of old plant material. Higher temperatures could lead to thawing of these frozen peatlands, and a lot of old material would then be transported into the Arctic Ocean. If this material is degraded it could release carbon dioxide or methane, creating an even stronger greenhouse effect. To see if this peatland material is being released, we will analyze specific compounds in the sediment cores that have a terrestrial origin (coming from trees, bushes, grasses etc.), so called “terrestrial biomarkers”.

Taking sediment cores. Photo: Jorien Vonk

By performing radiocarbon dating on these compounds, we can determine the age when the plant died and was frozen into the huge Siberian soil freezer better known as “permafrost”. If the top layers in the sediment cores appear older than deeper layers in the core, it is likely that recent climate warming is thawing this Siberian freezer!

All the cores we collect are sliced into 1 cm slices, that will be analyzed in our labs back in Stockholm. After this expedition, we will have hundreds of kilos of sediment! – enough for many years of work and hopefully nice publications?!

I now see icebergs passing by from the window in my cabin, so it’s time to have a look on the deck!

Hello,
Can you confirm the statement by Örjan Gustafsson to Dagens Nyheter that the seabed is releasing CH4? Is the water temperature at the bottom warm enough to allow the CH4 hydrates to melt? Also, where (lat-lon) and at what depth was this discovered? (shallow or deep water). How do these results differ from this earlier study:http://www.cosis.net/abstracts/EGU2007/01071/EGU2007-J-01071.pdf?PHPSESSID=e
Sorry, I don’t speak swedish, but as you understand, the world wants to know details. Thank you very much and good luck on your expedition.

Chief scientist is unwilling to yet release exact coordinates. We need to come home, evaluate and publish the data. The apporximate locations are two areas SSE of Virkitskyi strait in NW Laptev Sea, one area in fault zone east of Lena river mouth, and one location in area immediately outside western opening of Dmitri Laptev Strait.

Another CH4 maxima was found today in the East Siberian Sea off Yugosski Yar. We were unable to measure bottom seawater temperature at he first two location because of ice but will revisit sites on westward return transect.

There are several mechanisms whererby the subsea permafrost may thaw and warm bottom seawater is certainly a key contributing factor. For the interested person, I suggest to search for publications by Semiletov and Shakova et al in Geophysical Research Letters 2005 and Journal of Marine Systems 2007 and others.